This project consists of 49 subprojects, each of which comprises a separate question to be asked of our comprehensive computerized clinical data storage and retrieval systems. We have collected data on more than 5,700 kidney transplants performed at the University of Minnesota since 1968, and very comprehensive information on 3,600 patients transplanted since 1984. Multiple details (preoperative risk factors; tissue typing; the transplant admission and surgery; donor information; post transplant readmissions, rejections, biopsies, infections, and other complications; quality of life, rehabilitation) are available. New transplantas are entered prospectively; in addition, we are adding patients transplanted prior to 1984 into this database. Two types of studies are planned--retrospective and prospective. In some of these subprojects, data collection has been completed and analysis is planned. In others, long-term follow-up is required. Our computer database permits us to study transplant risk factors to an extent that has not previously been possible. The computer allows analysis of mini-series of subgroups of patients and/or multivariate analysis of the importance of risk factors. Among the most important of the subprojects are: A. Impact of "hypercoagulability" on graft loss; D. Is C4d staining helpful in interpreting renal allograft biopsies?; G. Outcome in relation to recipient risk factors; J. How can outcome be maximized for recipients with failing grafts?; R. Is long-term outcome improving for current recipients?; T. Skin cancer; U. Defining slow graft function; W. Relationship between bone disease and cardiovascular disease; X. Ongoing studies on nondirected donation; II. Risk factors in diabetic and non-diabetic recipients.